Relief valve



May 29, 1945. M. R. CROWE I ,3 1

' RELIEF VALVE i Filed Sept; 2, 1942 v 34 Fig.1.

\ lnvenTor Matthew R Qrowe Patented May 29, 1945 UNITED STATES PATENT OFFICE RELIEFVALVE Matthew R. Crcwe, Winthrop, Mass. Application September 2, 1942, Serial No. 456,999

1 Claimwater heaters, and the like, and it has for oneof its objects ,to provide a relief valve having novel temperature-responsive means for relieving the pressure in the boiler or other container when excessive temperature develops therein.

A further object of the invention is to provide a relief valve which not only has such a temperature-responsive means but which also has apressure-responsive valve adapted to open to relieve the pressure in the boiler or other container when excessive pressure develops therein.

In the present invention, the valve through which the pressure is relieved when excessive temperature develops in the container is arranged to be opened against the container pressure, and the temperature-responsive device comprises a thermostatic element situated on the discharge side of the valve and rendered operative to open the valve against the container pressure by heat that is transferred through a heat transfer element which extends through the valve and has a portion exposed to the temperature in the container.

In the drawing wherein I have illustrated a selected embodiment of the invention,

Fig. 1 is a vertical sectional View through a relief valve made in accordance with my invention,

said section being taken on the line I-I, Fig. 2.

of a boiler or other hot water container such as might be used in hot water heating systems. The

relief valve embodying my invention is indicated generally at 2, and it comprises a casing 3 having an inlet port 4 which communicates with the interior of the boiler or container I, and also having an outlet or discharge port 5 communicating with a waste pipe 6. This valve casing maybe secured to the container in any appropriate way, and it is herein shown as provided with an exteriorly screw-threaded nipple I adapted to be screwed into a boss E with which the container I is provided.

The inlet port 4 and the discharge port 5 have communication with each other through two different channels or passages formed in the casing 3. One of these passages is normally closed by the temperature-responsive valve which is automatically opened when the excessive temperature develops in the container I, and the other passage is normally closed by a pressured-responsive valve which is automatically opened when excessive pressure develops within the container I,

The first of the above-mentioned passages comprises a chamber 9 communicating with the discharge port 5, a second chamber ID communieating with the inlet port 4, and an opening II formed in a partition I2 separating the chambers 9 andIIh The temperature responsive valve is indicated at I3, and it is adapted to be seated against a valve seat I4 on the inlet side of the opening II. This valve I4 is therefore an inwardly opening valve and it is unseated against the pressure in the container I.

The temperature-responsive means by which the valve is unseated when excessivetemperature is, developed in the container I comprises a thermostatic element I5, herein shown as a metal bellows which expands in the direction of its length under the influence of a rising temperature and Whichis situated in the chamber 9 on the discharge side of the valve I3. One end of this'bellows structure I5 is secured to the valve I3, and the other is anchored in some suitable way to the valve casing 3. Associated with the valve and the thermostatic element I5 is a heat transfer member, the function of, which is to transfer sufiicient heat to the thermostatic element I5 when excessive temperature develops in the container I to cause the bellows I5 to expand sufficiently to unseat the valve I3 against the pressure in the container I. This heat transfer element is shown as a rod I5 which extends through the valve I3 and has a portion Il exposed to the temperature in the container I, and has another portion! situated within the bellows element I5. The end I! of this rod I6 will have a temperature the same as that of the fluid, whether it be water or steam, in the upper part of the container I and in the chamber I0 and the heat absorbed by the end I] of the heat transfer element I6 will flow through said rod to the end I8 and will thereby transfer heat to the thermostatic element.

So long as normal temperature exists in the boiler I, the thermostatic element I5 will be inoperative and the valve I3 will be retained on its seat thereby closing the port or opening II, If, however, excessive temperature develops in the container I, the temperature of the end I! of the heat transfer member It will be correspondingly raised, and said member I6 will transfer sufficient heat to the-thermostatic element l5 to cause it to expand sufliciently to force the valve I3 off from its seat I4 against the pressure in the container, thereby relieving such pressure.

As the temperature in the container I decreases from its excessive point, the bellows I5 will again contract, and the valve I3 will be automatically seated.

The outerend of th bellows I5 may be anchored to the casing 3 in any desirable Way. As herein shown said outer end of the bellows is provided with an exteriorly screw-threaded extension I9 which has a screw-threaded engagement with a plug 20 that is screw-threaded into the casing 3 and forms a closure for the end of the chamber a. This extension I9 is shown as formed with a screw driver slot ZI thereby providing for adjusting the anchored end of the thermostatic member 15 relative to the casing 3, By this means the bellows member I may be put under more or less of an initial tension and thereby the thermostatic element can be adjusted to open the valve I3 at different predetermined temperatures.

The extension I9 is shown as extending through the plug 20, and a protective cap 22 is screwthreaded to the end of the extension so as to protect the latter.

The other passage through the casing 3 in which the pressure-responsive valve is located comprises a valve chamber 23 which communicates with the chamber 9 through an opening 24, another chamber 25 which communicates with the chamber IIl through an opening or port 26 and an opening 21 which connects the chambers 23 and 25.

The pressure-responsive valve is indicated at 28, and it is adapted to seat against the valve seat 29 formed on the discharge side of the opening 21. This valve 28 is thus an outwardly opening valve. It is yieldingly held to its seat by a compression spring 30 one end of which engages the back side of the valve and the other end of which is backed by a screw-threaded plug 3| which is adjustably mounted in the casing for the purpose of varying the tension on the spring 30, This plug 3I is shown as screw-threaded into a cap 32 which in turn is screw-threaded into the casing 3, and the plug 3| is shown as having a screw driver slot 33 by which it can be turned to advance or retract it for the purpose of varying the tension on the spring 38. 3a is a removable closure plug screwthreaded into the cap 32 and serves the purpose of protecting the screw threaded plug, 3|.

So long as the pressure in the container I is normal or is below a critical point, the valve 28 will be held to its seat by the action of the spring 30.

If, however, excessive pressure develops in the container I, then such pressure will unseat the valve 28 against the action of the spring 30 thereby allowing the fluid in the container, whether water or steam, to escape through the discharge port 5 and waste pipe 6.

When the excessive pressure has been relieved, and the pressure in the container I returns to normal, the spring 30 will automatically seat the valve 28.

I have provided herein a venting valve constructed to allow the air in the container I to escape when it is first being filled and which is also operative to admit air to the container, if conditlons arise under which the pressure in the container becomes less than atmospheric pressure.

The valve 28 is provided with a depending stem 35 which has an axial bore or duct 36 extending therethrough. Screw-threaded to the lower end of the stem 35 is a cap or valve retainer 31 within which is located. a venting valve 38 that is adapted to close the lower end of the duct 36. This valve is shown as having a guiding stem 39 extending upwardly therefrom into the duct and another guiding stem 40 depending therefrom which extends through an aperture in the cap or container 31, This cap or valve retainer is provided with one or more ports 4 I.

When the container is empty, the valve 38 will assume its open positionshown in Fig.3 by gravity; and with the valve in thisposition, the air in the container is free to escape through the port M and duct 36 as the container is being filled.

When the container is filled with fluid under pressure, such pressure will close the valve 38 and hold it closed, said valve remaining closed so long as pressure exists in the container I.

If for any reason the pressure in the container I falls below atmospheric pressure, as might be the case if the Water in the container I was being siphoned out, then the venting valve 38 will open to allow air to enter the container and prevent its collapse.

42 indicates a fusible plug normally filling an opening in the stem 35. Such fusible plug is an additional means for relieving the pressure in the container I when excessive temperature develops in said container. If for any reason, the thermostatic bellows I5 should fail to operate to unseat the valve It When excessive temperature has developed in the container I, then such excessive temperature will fuse the plug 42 and thus allow the steam in the container I to escape to the waste pipe 6 through the bore 36 of the valve stem 35.

Thefusible plug 42 will preferably be of such a nature that it will not fuse under the temperature at which the thermostatic element I5 would normally operate to unseat the valve I3.

I claim:

A relief valve device for a container for hot water, said relief valve device comprising a valve casing having an inlet port in its bottom communicating with said container and an outlet port above the inlet port, two passages connecting the inlet and outlet ports, each passage having a vertically extending portion, one passage having a downwardly facing valve seat and the other passage having an upwardly facing valve seat, a downwardly and inwardly opening valve normally seating against the downwardly facing valve seat and closing the corresponding passage, means responsive to excessive temperature in said container to unseat said valve against the pressure in the container, said means bein located partly on the discharge side of said downwardly opening valve and partly on the inlet side thereof, an upwardly and outwardly opening pressure relief valve normally seating against the upwardly facing valve seat and closing the corresponding passage, a spring yieldingly holding said latter valve to its seat whereby excessive pressure in the container will unseat the upwardly and outwardly opening valve, said latter valve having a downwardly extending stem and also having an axial bore therethrough and through the stem, which bore provides another passage between the inlet and the outlet ports and terminates at its lower end in a downwardly facing valve seat, a downwardly opening venting valve co-operating with said latter valve seat to close said bore, said venting valve having a stem depending therefrom, and a cap retainer screw-threaded to the lower end of said last-named stem, which cap retainer has an axial bore to receive the stem of the venting valve, said cap retainer limiting the opening movement of the venting valve and the latter being held to its seat by the pressure within the container thereby closing said bore but adapted to open by gravity when there is no pressure in the container, thereby providing a vent for the discharge of air when the container is being filled.

MATTHEW R. CROWE. 

